Thermal circuit breaker



Nov. '14, 1933. G. o. WILMS 7 1,935,257

THERMAL CIRCUIT BREAKER Original Filed Oct. '15, 1927 Patented Nov. 1 4, 1933 PATENT OFFICE THERMAL CIRCUIT BREAKER Gustav 0. Wilms, Milwaukee, Wis., assignor, by mesne assignments, to Allen-Bradley Company, Milwaukee, Wis., a corporation of Wisconsin Application October 15, 1927, Serial No. 226,386 Renewed April 3, 1935 28 Claims. (Cl. 200-124) The invention relates to a thermal circuit breaker of the type in which is employed a ratchet latch retained by a fusible binder from being released.

The invention has as an object to provide a circuit breaker which is simple and efiicient and which is accurate in responding to predetermined conditions.

Another object is to provide a circuit breaker in which the rate at which heat is delivered to the fusible binder may be readily adjusted to vary the conditions under which the latch will be released.

Another object is to provide a circuit breaker which may be readily and economically manufactured.

Another object is to provide a circuit breaker in which the switch, the latch, and the electric heater are separate entities.

According to the invention in its general aspect as it is ordinarily embodied in practice, the circuit breaker is provided with a switch to control an electric circuit, a ratchet latch to control the switch and having a ratchet wheel arranged upon one side of a support and retained in a fixed position by a fusible binder, and a heat conductor heat insulated from the support and the switch and extending through the support to conduct heat therethrough to the binder.

The invention from other aspects will be apparent from the hereinafter description thereof.

The invention is exemplified by the circuit breaker illustrated in the accompanying drawing in which the views are as follows:

Fig. 1 is a side view of the circuit breaker.

Fig. 2 is an end view of the same.

Fig. 3 is a plan View.

Fig. 4 is'a vertical section on the line 44 of Fig. 2.

The circuit breaker is provided with a pivoted actuator 1 to engage the movable contact of a switch 2 which is biased to open position.

The actuator 1 is retained in a position to keep the switch closed by a pawl 3 engaging a ratchet in a stationary position thereon by a fusible binder 7.

The spindle 6 extends through one side of the frame 5 to conduct heat therethrough to the binder 7 from an electric heater 8 which is arranged upon the outer end of the spindle for connection into the electric circuit to be controlled.

The heater 8 is arranged upon the outside of the frame 5 to be readily accessible for connec tion into an electric circuit and for replacement.

The actuator 1 is arranged between the two sides of the frame 5 and pivoted upon a pintle 9 which is spaced from the spindle 6 and carriedby the opposite side of the frame.

The actuator is provided at its lower end with a roller 10 to engage the movable contact of the switch 2 and intermediate its ends with a pin 11 upon which the pawl 3 is pivoted.

The pawl 3 is urged into engagement with the ratchet wheel 4. by a spring 12, and it is provided ?5 with a lever 13 by means of which it may be disengaged from the ratchet wheel during the testing of the circuit breaker.

The actuator is provided with a spring 14 which urges it in a direction to release the switch and. 8G with a handle 15 by which it may be moved to a position to close the switch, in which position it is retained by engagement of the pawl with the ratchet wheel.

When the motor or other appliance is subjected to a predetermined overload, the heater 8 will generate sufiicient heat to fuse the binder '3' and release the ratchet wheel 4, permitting the spring 14 to rotate the actuator 1 sufficiently to allow the switch 2 to open and break the circuit.

The spindle 6 is heat insulated from the frame 5 by a heat insulating bushing 16 and from the pintle 9 by an air gap to limit the heat dissipated and thus increase the heat available to-fuse the binder. Consequently, a small size heater will suflice.

The resistance or heating element of the heater is selected to correspond to the characteristics of the motor or other appliance to be protected and, if in the form of a coil, the characteristics 1.00 thereof may be varied by varying the gage of resistance wire used, the number of turns in the coil, and the diameter of the coil relatively to the diameter of the heat conductor or spindle 6.

By conducting the heat from the heater to the fusible binder, instead of heating the ratchet wheel support or depending upon an accumulation-of heat according to the usual practice, a portion of the heat generated is dissipated by radiation so that small and harmless overloads will not cause the binder to fuse, larger overloads may be carried for predetermined periods of time before the binder is fused, and a very large overload will cause the binder to fuse almost instantly as sufficient heat cannot be radiated instantly to prevent fusing the binder.

When the switch is opened, the low fusing binder will harden quickly to again hold the ratchet wheel from rotation on the spindle.

The circuit breaker may be reset by pressing the handle of the actuator to close the switch where,- upon a new engagement is made by the pawl and ratchet wheel and the actuator locked thereby.

The circuit breaker herein set forth is ordinarily employed as a relay to control an electromagnetic switch and the heater 8 is ordinarily connected into the circuit controlled by the electromagnetic switch, but the circuit breaker may be employed for other purposes.

The circuit breaker which is herein set forth may be modified in various ways Without departing from the invention embodied therein and hereafter claimed.

The invention is hereby claimed as follows:

1. A circuit breaker, comprising an electric switch, a supporting frame carrying a heat conductor heat insulated therefrom, a pivoted switch actuator having its pivot arranged in axial alinement with said heatconductor, a serrated wheel retained in a fixed position upon said heat conductor by a fusible binder, a detent carried by said actuator and engaging said serrated wheel to keep said switch closed, and means to heat said heat conductor and thereby open said switch.

2. A circuit breaker, comprising a metallic sup- I port, a heat conductor extending through said support and heat insulated therefrom, a serrated wheel carried by said heat conductor and retained in a fixed position thereon by a fusible binder, a det'ent engaging said serrated wheel, an electric switch retained in a closed position by said detent, and means to heat said heat conductor to fuse said binder and thereby release said switch.

3. A circuit breaker, comprising a metallic support, a heat conductor extending through said support and heat insulated therefrom, a serrated wheel carried by said heat conductor and retained in a fixedp'osition thereon by a fusible binder, a detent engaging said serrated wheel, an electric switch retainedin a closed position by said detent, and an electric heater thermally associated with said heat conductor.

4. A circuit breaker, comprising a metallic support, a heat conductor extending through said support and heat insulated therefrom, a serrated wheel carried by said heat conductor and retained in a fixed position thereon by a fusible binder, a switch actuator carried by said support apart from said heat conductor and having its pivot arranged in axial alinementwith said heat conductor, a detent carried by said actuator and engaging said serrated wheel, an electric switch operated by said actuator and retained in a closed position by said detent engaging said serrated wheel, and means to heat said heat conductor and thereby fuse said binder to release said switch.

5. A circuit breaker comprising a heater for connection into an electric circuit, a heatinsulated heat conductor having one end thereof arranged in intimate thermal association with said heater to conduct heat therefrom, a ratchet wheel arranged upon the other end of said conductor and retained in a stationary position thereon by afusible binder, a separate switch to control said circuit, an actuator to control said switch carried by a pivot arranged in axial alinement with said conductor and spaced therefrom, a spring urging said actuator toward switch-open ing position, and a catch engaging said ratchet wheel to hold said switch closed.

6. A circuit breaker comprising a heater for connection into an electric circuit, a heat insulated heat conductor having one end thereof arranged in intimate thermal association with said heater to conduct heat therefrom, a ratchet wheel arranged upon the other end of said conductor and retained in'a stationary position thereon by a fusible binder, a separate switch biased to open position and controlling said circuit, an actuator to operate said switch carried by a pivot arranged in axial alinement with said conductor and spaced therefrom, a spring urging said actuator in a direction to permit said switch to open, and a spring pressed pawl pivoted upon said actuator and engaging said ratchet wheel to hold said actuator in switch-closing position.

7. A circuit breaker comprising a frame, a heat conductor carried by said frame and heat insulated therefrom, a heater carried by said conductor for connection into an electric circuit, a ratchet wheel arranged upon said conductor and retained in a stationary position thereon by a fusible binder, a pivot carried by said frame and spaced from said conductor, an actuator carried by said pivot, a switch'operated by said actuator, and a pawl carried by said actuator and engaging said ratchet wheel to hold said switch closed.

8. A circuit breaker comprising a frame having two spaced apart supports, a heat conductor carried by one of said supports and heat insulated therefrom, a heater arranged contiguous to the outer end of said conductor for connection into an electric circuit, a ratchet wheel arranged upon the inner end of said conductor and re tained in a stationary position thereon by a fusible binder, a pivot carried by the other support in axial alinement with said conductor and spaced therefrom, an actuator carried by said pivot, a switch operated by said actuator, and a pawl carried by said actuator and engaging said ratchet wheel to hold said switch closed.

9. A circuit breaker comprising a frame having two spaced apart supports, a heat conductor carried by one of said supports and heat insulated therefrom, a heater carried by the outer end of said conductor for connection into an electric circuit, a ratchet wheel arranged upon the inner end of said conductor and retained in a stationary position thereon by a fusible binder, a pivot carried by the other support in axial alinement with said conductor and spaced therefrom, an actuator carried by said pivot, a switch operated by said actuator, and a pawl carried by said actuator and engaging said ratchet wheel to hold said switch closed.

10. A circuit breaker comprising an insulating base, a frame arranged upon said base and having two spaced apart supports, a heat conductor carried by one of said supports and heat insulated therefrom, a heater arranged contiguous to the outer end of said heat conductor for connection into an electric circuit, a ratchet wheel arranged upon the inner end of said heat conductor and retained in a stationary position thereon by a fusible binder, a pivot carried by the other support in axial alinement with said heat conductor and spaced therefrom, an actuator carried by said pivot, a switch arranged upon said base and operated by said actuator, and a pawl carried by said actuator and engaging said ratchet wheel to hold saidswitch closed.

in a stationary position thereon by. a fusible binder, a pivot carried by the other support in to conduct heat from one side to the other side thereof and having one of its ends arranged within said heater to be heated thereby, a separate switch, and a latch controlling said switch and arranged upon the other side of said support and having a part thereof carried by the other end of said conductor and retained in a fixed position thereon by a fusible binder.

13. A circuit breaker, comprising a support, 'a heater arranged upon one side of said support for connection into an electric circuit, a heat insulated heat conductor carried by said support to conduct heat from one side to the other side of said support and having a part thereof arranged in intimate thermal association with said heater to be heated thereby, a separate switch biased to open position, and a latch controlling said switch and arranged upon the other side of said support and having a part thereof carried by another part of said conductor and retained in a fixed position thereon by a fusible binder.

14. A circuit. breaker, comprising a support, a heater arranged upon one side of said support for connection into an electric circuit, a heat insulated heat conductor carried by said support to conduct heat from one side to the other side "thereof and having one of its ends arranged in intimate thermal" association with said heater to be heated thereby, a serrated wheel arranged upon the other side of said support and carried thereby the other end of said conductor and retained in a fixed position thereon by a fusible binder, a switch having'its circuit independent of said wheel, an actuator to control said switch, a spring to operate said actuator, and a detent carried by said actuator and engaging said wheel to hold said actuator in a stationary position.

15. A circuit breaker, comprising a heater for connection into an electric circuit, a heat insulated heat conductor to conduct heat from said heater and having one of its ends arranged within said heater to be heated thereby, a serrated,

wheel arranged upon the other end of said conductor and retained in a stationaryv position thereon by a fusible binder, a switch having its circuit independent of said wheel, an actuator to 16. A circuit breaker, comprising a heater for connection into an electric. circuit, a heat insulated heat conductor to conduct heat from said heater and having one of its ends arranged in intimate thermal association with said heater to be heated thereby, a serrated wheel arranged upon the other end of said conductor and retained in a stationary position thereon by a fusible binder, a switch having its circuit independent of said wheel, an actuator to control said switch,

and a pawl pivoted upon said actuator and en-' gaging. said wheel.

17. A circuit breaker, comprising a frame having two spaced apart supports, a heat conductor carried by one of said supports and heat insulated therefrom, a heater arranged in intimate thermal association with the outer end of said conductor and adapted to be connected into an electric circu't, a serrated wheel arranged upon the inner end of said conductor andretained in a fixed position thereon by a fusible binder, a pivot carried by the other support and spaced from said conductor, an actuator carried by said pivot, a switch operated by said actuator, and a detent carried by sad actuator and engaging said wheel' to hold said switch closed.

18. A circuit breaker, comprising an insulating base, a frame arranged upon said base and having two spaced apart supports, a heat conductor carried by one of said supports and heat insulated therefrom, a heater arranged in intimate thermal association with the outer end of .said heat conductor for connection into an electric circuit, a serrated wheel arranged upon the inner end of said heat conductor and retained in a fixed position thereon by a fusible binder, a pivot carried by the other support and spaced from said heat conductor,'an actuator carried by said pivot, a switch arranged upon said base and operated by said actuator, and a detent engaging said wheel and holding said actuator in a stationary position.

19. A circuit breaker, comprising a support, a heat conductor extending through said support, a heating coil arranged around the end of said heat conductor upon the outer side of said support for connection into an electric circuit and to be readily accessible,a switch having its circuit independent of said conductor, and a latch controlling said switch and arranged upon the inner side of said support and having a part thereof fixed by a fusible binder upon the other end of said conductor.

20. A circuit breaker, comprising a support, a heat conductor extending throughsaid. support and heat insulated therefrom, a heating coil arranged around the end of said heat conductor upon the outer side of said support for connection into an electric circuit and to be readily removable, a switch having its circuit independent of said conductor, and a latch controlling said switch and arranged upon the inner side of said support and having a part thereof fixed by a fusible binder upon the other end of said conductor.

g 21. Arcircuit breaker, comprising a support, a

heat conductor extending through said support,

a heating coil to heat said heat conductor arranged upon the outside of said support for connection with the circuit to be controlled and to be readily accessible, ,a switch having its circuit independent of said conductor, a serrated wheel arranged upon the inside of said support and fixed to said heat conductor by a fusible binder, and a detent to engage said wheel and hold said switch closed.

22. A circuit breaker, comprising a support, a heat conductor extending throughsaid support and heat insulated therefrom, a heating coil to heat said heat conductor arranged upon the outside of said support for connection with the circuit to be controlled and to be readily removable, a separate switch, a serrated wheel arranged upon the inside of said support and fixed to said heat conductor by a fusible binder, and a detent to engage said wheel and hold said switch closed.

23. A circuit breaker, comprising an electric switch having a pivoted actuator biased in a predetermined direction, a heat conductor spaced from said switch and its actuator to heat insulate it therefrom and independent of the circuit controlled by said switch, a serrated wheel arranged upon said heat conductor in axial alinement with the pivot of said actuator and retained in a stationary position thereon by a fusible binder adapted to be fused by heat conducted thereto by said heat conductor, and a detent carried by said actuator and engaging said Wheel to prevent said switch from operating.

24. A circuit breaker, comprising an electric switch having a pivoted actuator biased in a-predetermined direction, a support, a heat conductor carried by said support apart from said switch and its actuator and independent of the circuit controlled by said switch, a serrated wheel arranged upon one side of said support in axial alinement with the pivot of said actuator and retained upon said heat conductor by a fusible binder, a detent to engage said wheeland prevent said switch from operating, and a heater arranged upon the other side of said support to heat said conductor.

25. A circuit breaker, comprising an electric switch having an actuator pivoted upon a support and biased in a predetermined direction, a heat insulated heat conductor extending through said support to conduct heat from one side to the other side thereof and carried by said support apart from the pivot of said actuator and independent of the circuit controlled by said switch,

a serrated wheel arranged upon one side of said support apart from said switch and retained in a stationary position upon said heat conductor by a fusible binder to be fused by heat conducted thereto from the other side of said support by said heat conductor, and a detent to engage said wheel and retain said actuator in a stationary position.

26. A circuit breaker, comprising an electric switch having an actuator pivoted upon a support and biased in a predetermined direction, a heat insulated heat conductor extending through said support to conduct heat from one side to the other side thereof and carried by said support apart from the pivot of said actuator and independent of the circuit controlled by said switch, a serrated wheel arranged upon one side of said support apart from said switch and retained in a stationary position upon said heat conductor by a fusible binder, a detent to engage said wheel and retain said actuator in a stationary position, and a heater arranged upon the other side of said support to heat said heat conductor.

27. A circuit breaker, comprising a switch to control an electric circuit, a support, a ratchet latch retaining said switch in a predetermined position and having a ratchet wheel arranged upon one side of said support and retained in a fixed position by a fusible binder, and a heat conductor heat insulated from said support and said switch and extending through said support to conduct heat therethrough to said binder.

28. A circuit breaker, comprising an electric switch having a pivoted actuator biased in a 

